It is well known that there are several microbial species found in soil and water that are capable of assimilating petroleum hydrocarbons. Unfortunately, the rate of microbial assimilation of petroleum hydrocarbons is relatively slow. It is necessary, therefore, to enhance the biological process if bioremediation is to be applied as a practical soil and water decontamination process.
In general, the rate and extent of microbial utilization of petroleum hydrocarbons is limited by the concentration of microbial nutrients and microflora available at the hydrocarbon-water interface. Thus, microbial nutrients, especially nitrogen containing nutrients like urea and ammonium nitrate have been added to contaminated soil or water as a method for enhancing the biodegradation of the hydrocarbon contaminants. Because these nitrogen containing microbial nutrients are generally water soluble and because the petroleum hydrocarbons are hydrophobic, the nutrients are generally delivered in an aqueous solution, along with a surface active agent which makes the contaminant bio-available to the hydrocarbon degrading microbes.
Notwithstanding the benefits resulting from using aqueous solutions of microbial nutrients, trace metals like Fe, Cu, Ni, Zn, Co and Mn are also useful as additional microbial nutrients. These metals are typically delivered in aqueous solution, often in the form of a complex with ethylene diamine tetraacetic acid (EDTA). Although this approach is useful, there remains a need for better approaches to making microbial nutrients and trace metals bio-available to the microbes at the hydrocarbon contaminant-water interface.
One object of the present invention therefore is to enhance the bioavailability of microbial nutrients by providing molecules that are surface active and have nutrient attributes.
Another object of the present invention is to provide a composition and method for stimulating the propagation of naturally occurring hydrocarbon assimilating microflora to enhance the bioremediation of hydrocarbon contaminated water and soils.